The present invention is directed to a multicoordinate sensing head of the type which is adapted to be mounted to a measuring or processing machine and which includes a casing and a sensing pin having a sensing end and a mounting end.
Such sensing arrangements are used in conjunction with coordinate measuring machines as well as in numerically controlled processing machines. Typically, such sensing arrangements or heads are used in order to sense or detect the dimensions of the workpiece and/or tool.
A wide variety of such sensing heads are known to the art, and the following discussion will take up only two examples of such sensing heads.
German DE-AS No. 19 32 010 discloses a sensing head in which the sensing pin is mounted in a casing by a ball joint arrangement. The end of the sensing pin disposed opposite the sensing end of the pin bears against an axially slidable sleeve which acts upon a measuring value converter so that each deflection of the sensing pin in either the axial or the radial directions results in an axial displacement of the sleeve, which is measured and registered by the measuring value converter.
British Pat. No. 1,599,758 discloses a sensing head which generates an electrical signal upon contact between a sensing pin and a workpiece. This electrical signal is generated by the closing of an electrical circuit between the electrically conductive workpiece and the sensing head. The sensing pin of this sensing head defines a spherical sensing surface, and the sensing pin is mounted so as to be linearly displaceable with respect to the casing. The end of the sensing pin opposite the sensing end is mounted to be linearly displaceable inside the scanning head casing in a cylindrical sleeve. When the sensing pin is deflected, the end of the sensing pin opposite the spherical sensing surface is shifted axially. The sensing pin defines, in the interior of the sensing head casing, a flange. The circumferential edge of this flange abuts against the bottom of the sensing pin casing thereby causing the sensing pin to tilt on radial deflection of the sensing surface. During such tilting, the sensing pin is radially displaced, which causes a coaxial movement of the radially constrained upper end of the sensing pin. When tilting forces are removed from the sensing pin, a resetting spring operates to return the sensing pin into a zero or rest position. The radially constrained upper end of the sensing pin determines the X and Y coordinates of this rest position and the face surface of the flange secured to the sensing pin serves as a stop in the axial or Z direction. The sensing head disclosed in this British patent relies upon electrical contact being made between the workpiece and the sensing pin, and this sensing head is therefore unusable when an electrically nonconductive workpiece is to be sensed.